2nd Gen Non-Engine/Transmission Another A/C problem

[LCampbell]

Had the A/C system serviced in my 02 2500 last October & now it's not putting out any cold air in normal or max A/C with the temp. controller at any position on the cold side. The shop supposedly put dye in the system but I haven't seen any evidence of a leak. Things I've checked. The fan clutch seems to be operating normally. The compressor clutch engages for several seconds & then disengages for several seconds & then repeats (Low on r134?) I can see the blend door actuator turning when I move the temp. control. The recirc air door operates normally & I checked the vacuum system for leaks. It holds a vacuum when I test it with a mity vac. The vacuum pump pulls 22. 9'' at idle & 23" at 2000rpm. I pulled the blower fan out & felt around inside for evidence of the dye & didn't find anything. Could this possibly be the dreaded evaporator leak? Thanks in advance.

 

[BHanna]

The clutch only staying on for a couple seconds sounds like you could have a leak. You really need some gauges to be sure. It may be your low-pressure switch is bad or set wrong and is kicking the clutch off.

If your r134 is low and you can't find the dye, a good A/C shop will have a sniffer that can usually find the leak.

I'm not sure how many other people have this problem but I definitely do. One of my schrader valves vibrates loose once in a while. Did you take the caps off those and look for dye there?

 

[LCampbell]

Are you talking about the valves where you attach the gauges? Mine don't look like schrader valves. Nothing to tighten. It looks like a small ball check valve. Thanks for the info on the low pressure switch. Maybe I'll replace it.

 

[B.G. Smith]

Are you talking about the valves where you attach the gauges? Mine don't look like schrader valves. Nothing to tighten. It looks like a small ball check valve. Thanks for the info on the low pressure switch. Maybe I'll replace it.

There are supposed to be caps on the fittings, that could be where your leak is, also some of the dye is only visible with a black light. Even if you have a leak it might be very slow, I would try a recharge and see how long it lasts??? I spent about 30 years in refrigeration maintenance/repair and the experts always told us that only refrigerant and the correct oil should be put into the system. It worked for me. bg

 

[Crowhurst]

The compressor clutch engages for several seconds & then disengages for several seconds & then repeats (Low on r134?) QUOTE]



The Chrysler shop manual at page 24-12 states that ten or more cycles per minute indicates a fault. Assuming a cycle is "on and off", then 3 seconds on and 3 seconds off is below the minimum for a properly working system. I just checked mine, and it's 5 seconds on and then 5 seconds off at idle when first switched on. If yours comes on for 3 seconds or less, the manual gives as possible causes:

1. Low refrigerant system charge.

2. Faulty low pressure cycling switch.

3. Faulty Power Control Module.



In case you don't have a copy, I should mention that the manual has 48 pages of excellent detail to assist in maintaining the AC.

Nick.

 

[vahunters]

mine is also leaking. $30 at Pep boys will buy you a AC refill kit and should last you for a while.

 

[madmanmanick]

some things to check

There are a few things to look at and think about. First, the refrigerant dye that the shop put in can only be seen under ultraviolet light with yellow glasses on. Second the shrader valves look like the ones on the valve stems of your tires. They screw in and out so it is possible that one of them has backed out a little and is not seating. Any shrader valve tool (about 10 dollars) for a tire will work to tighten them up. Now with the compressor engaging and disengaging. That sounds like a low charge which is causing the low pressure switch to disengage the compressor. The way to check this is to attach a gauge manifold set to the A/C system. A manifold set can be bought at any auto parts store for around 40-100 dollars. You can also buy a simple little single gauge that attaches to just the low side for about 20 dollars. With A/C at full you should have a low side reading of 32-40 and a high side reading of 190-220. If it doesn't reach those levels than that means you have low charge. Now if you go to an auto parts store and buy those little bottles of refrigerant make sure you buy one of the bottles of R-134a oil cans. And be sure not to overcharge the system cause that could cause more damage than the system being undercharged. Hope all this helps you.

 

[LCampbell]

Thanks to all for the advice & information. This forum is awesome. Wanted to get it fixed quickly before at trip next weekend so I took it back to the shop. They gave me an estimate for replacing the evaporator (approx $1000) But it turned out to be a leak at the high pressure switch. $183 total including parts. Putting out lots of cool air now.